Bottom hole gas-liquid separator



Nov. 5, 1968 W. J. HART, JR

BOTTOM HOLE GAS-LIQUID SEPARATOR Filed Nov. 22, 1966 I Fig. 3

INVENTOR. W41. 75/? J. HART, JR.

Fig. 2

Pig. 1

United States Patent 3,408,949 BOTTOM HOLE GAS-LIQUID SEPARATOR Walter J. Hart, Jr., Odessa, Tern, assignor to Gulf Oil Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Filed Nov. 22, 1966, Ser. No. 596,157 3 Claims. (Cl. 103-234) ABSTRACT OF THE DISCLOSURE Apparatus for intermittently producing fluids through a well producing gas and liquid under a pressure insufficient to cause flowing of the well in which a float tube encircling the lower end of production tubing is adapted to move vertically within a housing extending downwardly from the lower end of the production tubing. Ports in the upper end of the housing allow liquid to enter the housing and float the float tube to an upper position to close a valve in the lower end of the production tubing. Filling of the float tube causes the float tube to move to a lower position opening the valve and permitting liquid to enter the production tubing.

This invention resides in an apparatus for producing fluids from wells which are incapable of flowing naturally.

In the production life of a flowing oil well a static condition will be reached wherein there is insuflicient gas pressure to overcome the hydrostatic head created by fluid accumulation in the well bore. This condition is principally caused by a decrease of reservoir pressure. Another contributing factor to the termination of a wells ability to flow is the accumulation of formation water in the well bore which will produce a fluid hydrostatic head equal to the pressure of the gas which enters the Well bore.

As a well becomes watered out or the formation gas is depleted to the extent that production is seriously restricted or terminated, it has heretofore been necessary to periodically swab the well, thereby reducing the fluid hydrostatic head in the well bore, or install mechanical pumping equipment in the well. Either operation decreases the economic elficiency of producing oil, requires additional supervision and the utilization of expensive equipment.

This invention resides in an apparatus for intermittently producing fluids from wells which are incapable of flowing naturally. More specifically this apparatus is adaptable for use in Wells which produce suflicient gas pressure to flow intermittent slugs of fluids to the surface, if the fluid hydrostatic head within the well bore is maintained at a low value. This apparatus controls the height of fluid accumulating in the well bore by intermittently.

opening the well bore to deliver fluid from the well to the surface. A production valve arrangement, connected to the lower end of the production tubing and located within the housing of the apparatus, is actuated by a slidable float tube. In the filling cycle the slidable float tube is buoyed upward to a position closing the production valve. Gas and liquid entering the well bore during the filling cycle separate with the gas occupying the upper portion of the well bore. The liquid accumulating in the well bore enters the housing of the tool. After suflicient fluid enters the housing it will flow over and fill the float tube causing the float tube to sink to the bottom of the housing. The downward movement of the float tube will open the pro duction valve and allow liquid to be discharged from the bottom of the float tube through the production tubing to the surface. When the gas pressure exerted against the inside of the float tube is overcome by the force produced by the buoyancy of the float tube, the float tube will slide upward closing the production valve thereby starting a new filling cycle.

In the drawings:

FIGURE 1 is a diagrammatic view partially in vertical cross section showing the bottom hole separator of this invention with its float tube in the position for passing fluids to the surface.

FIGURE 2 is a diagrammatic view partially in cross section showing the bottom hole separator of this invention with the float tube sealing the production conduit and allowing fluids to accumulate prior to passing these fluids to the surface.

FIGURE 3 is a diagrammatic view partially in cross section showing another embodiment of the valve arrangement in the bottom hole separator of this invention.

Referring to FIGURE 1, production tubing 2 extends from the surface of the earth, downward through the borehole of a well (not shown) to a subterranean formation. A production conduit 4 is attached to the lower end of the production tubing 2. A valve seat 6 is mounted on the lower end of the production conduit 4. A slidable float tube 8 concentric with and encompassing the production conduit 4 is sealed on its lower end by a bottom member 10 to prevent fluid from entering the lower end of the fioat tube 10. A production valve plug 12 is mounted on the upper surface of the bottom member 10 positioned to engage the valve seat 6. Weight discs 14 are attached to the bottom of the float tube 8 and utilized to regulate the buoyance effect of the float tube 8.

A hollow housing 16 is attached at its upper end to the production conduit 4 and forms the outer surface of the tool. The sealed housing 16 has a float tube stop 18 mounted on its lower inner surface to limit the downward travel of the float tube. As preferred in this illustration, a sand trap is formed in the lower portion of the housing 16, below the float tube stop 18, to prevent sand from entering the tool and obstructing travel of the float tube 8. Fluid ports 20 are formed through the housing 16 at a higher elevation on the housing than the top of the float tube 8 contained therein. Outwardly extending splash plates 22 are preferably attached to the upper end of the production conduit 4 within the housing 16 and adjacent the fluid ports 20 to direct fluid into the housing annulus 24 between the housing 16 and the float tube 8.

In FIGURE 1, the float tube 8 has filled with fluid and moved to its lower position. The production valve 12 is thereby opened and fluid is passing up the production conduit 4, through the production tubing 2 and to the surface. The driving force of this fluid is produced by the gas which has accumulated in the well bore during the filling cycle.

FIGURE 2 shows the bottom hole separator of this invention in its filling position. Owing to the decreased volume of fluid within the float tube 8, the float tube -8 is buoyed by the fluid within the housing 16 to an upper position thereby sealing the production conduit 4.

FIGURE 3 is another embodiment of this invention in which sand trap 25 is formed with the float tube 8 by mounting the production valve 12 on the upper end of a spacer bar 26. The lower end of the spacer bar 26 is mounted on the upper surface of the bottom member 18. The float tube annulus 28 between the float tube 8 and the spacer bar 26 forms a trap for sand entering the float tube 8.

In the operation of this invention the float tube 8 is normally buoyed upward with the production valve 12 seated in the lower end of the production conduit 4 thereby sealing fluids from entering the production tubing 2 and producing an area of reduced pressure across the bottom of the float tube 8 caused by the reduction of pressure within the production conduit 4. As fluids enter the well bore from the formation, the gas will travel upward to the upper end of the well bore with liquids flowing into the housing annulus 24 through 3 the production ports 20. These liquids will fill the housing annulus 24 as the produced gases cause a build up of pressure above the tool. When the liquid level in the housing annulus 24 reaches the top of the float tube 8, liquids will begin spilling over and accumulating in the float tube 8. The liquid level within the float tube 8 will rise to a point where the hydrostatic head produced by the liquid in the float tube 8 overcomes the force pro duced by the buoyancy of the float tube 8 and the differential pressure across the bottom of the float tube 8. As these forces are overcome the float tube 8 will slide downwardly in the housing 16 to rest on the float tube stop 18. The downward movement of the float tube 8 will open the lower end of the production conduit 4 whereby the liquid within the float tube 8 will be in communication with the production tubing 2 to the surface. The gas accumulated above the tool will force the liquid from the bottom of the float tube 8 into the production conduit 4 and upwardly through the production tubing 2 to the surface.

As liquid passes from the float tube 8 to the surface, the level of liquid within the float tube 8 will be lowered with a resultant decrease in float tube Weight. The liquid on the outside of the float tube 8 will cause the float tube 8 to be buoyed upward thereby sealing the production conduit 4 and starting a new filling cycle.

It is obvious that the force produced by the bouyancy of the float tube of this invention is dependent upon the diameter of the float tube and the material from which it is constructed. Weight disks are attached to the float tube in order to make adjustments in the buoyancy effect which will match the preferred operation of the tool to the particular well in which it is installed. Compensation for low gas pressure may also be made by installing flow valves in the tubing to assure that the intermittent slug of fluid will be delivered to the surface. The amount of back pressure held on the production tubing by the surface gathering equipment may also be regulated to control the operation of this tool.

The installation of the bottom hole separator of this invention will enable the operator to extend the flowing life of the well. By so extending the wells flowing life, production costs will be decreased with a corresponding decrease in well supervision, maintenance and the utilization of producing equipment.

Iclaim:

1. Apparatus for intermittently producing fluids entering a well bore comprising a string of production tubing extending downwardly through the well bore from the surface of the earth to a level lower than the maximum height to which liquid rises in the well, a housing closed at its lower end secured to the lower end of the production tubing, said housing having entrance ports therein near the upper end thereof, a production conduit communicating with and extending downwardly from the lower end of the production tubing in the housing and terminating above the lower end of the housing, a float tube open at its upper end and closed at its lower end encircling the production conduit within the housing, said float tube being vertically movable between an upper position and a lower position, the internal diameter of the float tube being larger than the external diameter of the production conduit to provide an annulus therebetween, a valve port at the lower end of the production conduit, a valve plug extending upwardly from the lower end of the float tube in a position to engage the valve port when the float tube is in the upper position, and a splash plate extending outwardly from the production tubing beyond the float tube and between the upper end of the float tube and the entrance ports to deflect liquid entering the entrance ports from the annulus.

2. Apparatus for intermittently producing fluids entering a well bore comprising a string of production tubing extending downwardly through the well bore from the surface of the earth to a level lower than the maximum height to which liquid rises in the well, a housing closed at it lower end secured to the lower end of the production tubing, said housing having entrance ports therein near the upper end thereof, a production conduit communicating with and extending downwardly from the lower end of the production tubing in the housing and terminating above the lower end of the housing, a float tube open at its upper end and closed at its lower end encircling the production conduit within the housing, said float tube being vertically movable between an upper position and a lower position, the internal diameter of the float tube being larger than the external diameter of the production conduit to provide an annulus therebetween, a valve port at the lower end of the production conduit, a valve plug extending upwardly from the lower end of the float tube in a position to engage the valve port when the float tube is in the upper position, a stop protruding inwardly from the inner wall of the housing at a level spaced above the lower end thereof to limit downward movement of the float tube, and openings through the stop through which solid particles can settle into the housing below the stop.

3. Apparatus for intermittently producing fluids entering a well bore comprising a string of production tubing extending downwardly through the well bore from the surface of the earth to a level lower than the maximum height to which liquid rises in the well, a housing closed at its lower end secured to the lower end of the production tubing, said housing having entrance ports therein near the upper end thereof, a production conduit communicating with and extending downwardly from the lower end of the production tubing in the housing and terminating above the lower end of the housing, a float tube open at its upper end and closed at its lower end encircling the production conduit within the housing, said float tube being vertically movable between an upper position and a lower position, the internal diameter of the float tube being larger than the external diameter of the production conduit to provide an annulus therebetween, a valve port at the lower end of the production conduit, a valve plug extending upwardly from the lower end of the float tube in a position to engage the valve port when the float tube is in the upper position, and weighted discs mounted on the bottom of the float tube to control the buoyancy thereof.

References Cited UNITED STATES PATENTS 1,958,545 5/1934 Morris 103-40 X 2,122,080 6/1938 Wisdom 10340 2,128,475 8/1938 Rodgers 103-40 X 2,291,902 8/1942 Kelley 10340 3,324,803 6/1967 Kelley et al. 103232 FRED C. MATTERN, 121., Primary Examiner.

W. J. KRAUSS, Assistant Examiner. 

